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Audi R8 4.2 V8 6-speed manual vs Mercedes-Benz CLA45 AMG from a roll

The camera car here is an Audi R8 4.2 liter V8 and it is a 6-speed manual car. The R8 despite being a two seat sports car weighs about the same as the four-door CLA45 AMG. It also is roughly twice the price. Unlike the CLA45 AMG it is naturally aspirated with a 420 horsepower 4.2 liter V8 that revs to just over 8000 rpm. The CLA45 AMG has an engine less than twice the size and with half the cylinders. It is turbocharged though for 355 horsepower (and a bit underrated).

The CLA45 AMG does have a torque advantage with 332 lb-ft of torque to the 316 lb-ft of torque in the R8. Both have all wheel drive but the CLA45 AMG has a dual clutch transmission while the R8 has a 6-speed manual. So how does an entry level AMG sedan do against a $100k+ V8 Audi sports car (in the rain) ?

Incredibly well. The cars are surprisingly close until the top end of the 8000+ rpm Audi V8 allows it to open a slight gap. This race is much closer than the R8 owner likely expected. The less powerful entry level four cylinder Mercedes sedan sticks with the R8. All while having half the cylinder count, half the displacement, and half the price.

How can one not be impressed with what AMG has done with the 45 models?

coming from the audi world myself...last 12yrs modding them and just hopping over to BMW last year.
the R8 is sexy no doubt. but taking the RS4 motor and putting it in the R8 was very lack luster at best to describe it.
my last car was a modded NA S4. same 4.2 used but stock was 340hp while RS4 and R8 got the 420hp.
my modded S4 became faster than an RS4 and put up a good fight with R8 v8s...me winning at the beginning and losing at high RPM.
stock shift point was 7250...modded 7500. it was simple mods but effective mods that made the car what it was.
After the R8 V10 came out....the V8 was basically put out to pasture and treated like a redheaded step child. ever to been seen or spoken again.
I will say this is more of a fair fight...the v10 would hardly be an appropriate run again the CLA45. every r8 owner turned the v8 in for a v10.
who would want a high or mid 12 v8 for 120k when a modded s4 can smoke you or sit next to you. the 4.2L while i love it...the R8 deserved its own motor....so the stole
from lambo...though they make the lambo v10....so i guess its not stealing. technically. definite props to the CLA45 for holding ground.

Many of the R8 V8 engines (also concerns the RS4) have quite a bit less than the 420hp they should have on paper. Much of it due to heavyly carbonised intake valves that is a result of the direct injection.

That being said, the CLA still is quite fast. The R8 though has not been conceived for maximised straight-line performance. And the R8 V8 are quite popular despite of what someone else has written here, which is why Audi will continue to offer that engine in the next generation R8. The V10 certainly is much more fun, but for 99% of all situations in public traffic the V8 is sufficient.

You can boost the V8 though. It's still a better motor than the V8 S4. It's the same thing as the RS4 basically except with twin throttle bodies.

You boost it. But then this race would be completely unfair. They wouldn't need to race and also increasing the cost gap even more so

This is true. The did pump it up. But it's still a base s4 motor. Actually with a lot more tweaks. Cams n such. Which why none of us could convert over to the rs4 motor. We had to approach it a different way.
But NA.....we could still drop down to 12.6-12.7. Sum of the parts and the right ones at that. Nitrous low low 12s, s/c was held back n ran high 11s. The kit should have easily run low 11s or high 10s. But internals are a issue.

Many of the R8 V8 engines (also concerns the RS4) have quite a bit less than the 420hp they should have on paper. Much of it due to heavyly carbonised intake valves that is a result of the direct injection.

That being said, the CLA still is quite fast. The R8 though has not been conceived for maximised straight-line performance. And the R8 V8 are quite popular despite of what someone else has written here, which is why Audi will continue to offer that engine in the next generation R8. The V10 certainly is much more fun, but for 99% of all situations in public traffic the V8 is sufficient.

No its not popular anymore unless someone wants an R8 on the cheap. V8 is 109-120k. V10 was at 160k when i had my s4 serviced which was 2yrs ago. Its at 202k now.

Nobody cares about what is sufficient. They aren't buying these cars to be sufficient. Nothing sufficient about them.